The purification of gas streams is a critical component of many processes, including hydrocarbon gas production and semiconductor manufacturing.
Low quantities of undesirable mercury components are known to exist naturally in geological hydrocarbon sources, particularly for natural gases. Hydrocarbons may include alkanes, such as methane, ethane, propane, butane, pentane, hexane, etc, alkenes and alkynes. The alkanes, alkenes and alkynes may be liner, branched or cyclic. The exposure of aluminum-based equipment in natural gas processing plants to large volumes of trace mercury results in cumulative amalgamate formation, which can lead to corrosive cracking and equipment failure. There are also environmental and health concerns over the discharge of hazardous mercury contaminates, with regulations requiring the complete removal of mercury compounds from fuel-grade gas.
Current methods of removing trace mercury from hydrocarbon streams involve reactions of mercury with chemicals that are often supported on porous materials such as activated carbon, alumina, silica and zeolite. In semiconductor manufacturing, the purity of electronic gases used for the fabrication of solid state devices, such as transistors, diodes, light emitting diodes, lasers, solar cells, and capacitors, is important. As used herein, “electronic gases” are source gases used for doping (e.g. ion implantation, chemical vapor deposition (CVD), atomic layer deposition (ALD)) or layer deposition of semiconductor (e.g. Group IV, III-V, II-VI), insulators (e.g. silicon oxide, silicon nitride) and conductors (e.g. tungsten) in solid state devices. It is understood that trace quantities of electronic gas contaminates can have significant detrimental effects on the quality of semiconductor devices. These contaminants are commonly gaseous compounds that include acids, ammonia, amines, alcohols, carbon dioxide, carbon monoxide, hydrocarbons, hydrogen, hydrogen sulfides, nitrogen oxides, oxygen, siloxanes, sulfur dioxide, sulfur oxides and water. In particular, there is interest in the vigorous purification of hydride gases used in semiconductor manufacturing, such as ammonia, arsine, phosphine, diborane, disilane, germane and silane and other gases such as boron trifluoride. Current methods of hydride gas purification focus on the use of reduced metal and metal oxides. Large excess amounts of electronic gases are commonly used during the layer deposition of semiconductors, insulators, and conductors, which necessitates the removal of leftover unreacted electronic gases. Particularly for hydride gases, current conventional electronic gas abatement systems rely on dry scrubbers comprising of metal oxides, metal carbonates, and metal hydroxides.
Across all aforementioned applications of purification and abatement, the use of traditional porous materials, such as activated carbon, alumina, silica and zeolites, have shown to benefit the efficiency and reactivity of the active metal and non-metal components. It is understood that the available contact surface area of the active component is greatly increased when either mixed-in or supported onto these porous materials, enhancing the overall diffusion characteristics of these sorbents. However, further benefits and enhancements have been limited by the relatively low porosity and poor customizability of these porous materials. The ill-defined internal structure and irregular porosity for some of these materials also hampers performance